World number one Serena dropped serve just once as she crushed fifth seed Jelena Jankovic 6-2 6-2, although the match was tainted by another heated exchange on court between the pair.
"It definitely felt a lot more comfortable than my first match," said Williams.
"There were some shots I missed today that I would never have missed a month ago, so I'm still getting a little rust off, but it feels good overall. And I'm still trying to make sure I keep going in the right direction."
She will now face Alize Cornet in the last four after the Frenchwoman overcame Carla Suarez Navarro 7-5 6-3.
Serena’s older sister Venus beat Italy’s Flavia Pennetta 6-3 7-5.
The 33-year-old American never looked in danger against Pennetta, who had stunned second seed Agnieska Radwanska in the last-16.
This time, however, Pennetta found herself outgunned in straight sets by Williams, who has said this week that, "I just love the conditions here."
Alize Cornet (France) beat Carla Suarez Navarro (Spain) 7-5 6-3
1-Serena Williams (US) beat 5-Jelena Jankovic (Serbia) 6-2 6-2